Strongly Confined Bismuth Antimonide Quantum Dots

Bismuth antimonide (Bi_1-x Sb _x ) has emerged as a highly promising material for quantum applications due to its complex band structure. In this study, spherical Bi_1-x Sb _x quantum dots (QDs), with a diameter of around 8 ± 2 nm, were successfully synthesized by pulsed laser ablation in liquids. The energy bandgap was determined at 2.02 ± 0.27 eV, which is significantly higher than the bulk value (∼0.025 eV). The strong confinement nature of the dots was confirmed by the Raman peak shifts. The chemical composition of the Bi_1-x Sb _x QDs was measured to be around 77 ± 2 at. % of Bi and 23 ± 2 at. % of Sb. The colloid containing the Bi_1-x Sb _x QDs was classified as highly stable, displaying a zeta potential of -38 ± 18 mV. Finally, the Bi_1-x Sb _x QDs exhibited an electron spin resonance (ESR) signal at room temperature and at cryogenic temperature (4.2 K); consequently, revealing the presence of paramagnetic states.